Contributions to Understanding the Behavior of Axially Compressed Cylinders

Abstract

An elastic nonlinear Ritz analysis is used to investigate the behavior of axially loaded imperfect cylindrical shells. It is shown how the initially positive contributions arising from the shells membrane energy are eroded with increasing levels of both deformations and imperfections. This loss of membrane energy is shown to be responsible for the notoriously imperfection sensitive buckling of the shell. Extensive parameter studies demonstrate the existence of a well-defined lower bound to buckling loads and the dominance of characteristic incremental deformation modes as this lower bound is approached. For the first time the physically based hypotheses of the reduced stiffness method are theoretically demonstrated. Furthermore, it is shown how a slightly modified form of the reduced stiffness method provides very close predictions of the lower bounds to buckling loads.